为什么这个 PHP header() 重定向会陷入无限循环？
我有这段代码，应该获取当前日期，将其映射到设定的结束日期，并在当前日期超过结束日期时重定向。每当我将 $promoend 设置为过去的日期时，我就会陷入重定向循环。
if() 块仅应在促销已结束且我尚未位于 Closed.php 页面上时重定向。
$currentdate = new DateTime("now");
$promoend = new DateTime("11/01/2010 00:00:00");
$promoend = $currentdate->diff($promoend)->invert;
if ($promoend && !strpos($_SERVER["PHP_SELF"],"closed.php")) {
header("Location: ".$environment->root."/closed.php");
}
知道为什么这会陷入循环吗？
I have this piece of code that is supposed to get the current date, comapre it to a set end date, and redirect if the current date is past the end date. Whenever I set the $promoend to a past date, I get stuck in a redirect loop.
The if() block should only redirect if the promotion has ended and I am not on the closed.php page already.
$currentdate = new DateTime("now");
$promoend = new DateTime("11/01/2010 00:00:00");
$promoend = $currentdate->diff($promoend)->invert;
if ($promoend && !strpos($_SERVER["PHP_SELF"],"closed.php")) {
header("Location: ".$environment->root."/closed.php");
}
Any idea why this is caught in a loop?
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如果针（'close.php'）位于大海捞针（$_SERVER['PHP_SELF']）的开头，则 strpos 可以返回 0。这将被 PHP 视为“假”，因为您没有使用严格的比较运算符。
您必须使用严格比较运算符来检查这种情况：
strpos can return 0 if the needle ('closed.php') is at the start of the haystack ($_SERVER['PHP_SELF']). This will get treated as 'false' by PHP, as you're not using a strict comparison operator.
You MUST use the strict comparison operator to check for this case:
...可能应该是...
因为 strpos() 并不总是返回布尔值，所以您必须使用 PHP 等价运算符。
...should probably be...
Because strpos() does not always return a boolean so you have to use the PHP equivalence operator.
假设您的日期计算正确，原因是 strpos 返回 0，因为您在 PHP_SELF 中查找的字符串位于 0 位置。
您必须使用 !== "" 而不仅仅是 !val 因为 0 与 "" 相同，与 NULL 相同
Assuming your date calculations are correct the reason is, is that strpos is returning 0 because the string you are looking for in PHP_SELF is at the 0 position.
You have to use !== "" instead of just !val because 0 is the same as "" is the same as NULL